Design of a remote data subscription mechanism

The CERN 26 GeV Proton Synchrotron (PS) accelerator complex produces a sequence of different beams in cycles of a duration of 1.2 sec or multiple of it. A Main Control Room operator, supervising the functioning of (part of) an accelerator for a particular beam, needs to coherently display on his workstation the beam-dependent data in synchronism with this particular cycle (within a certain time delay). The classical data collection via synchronous Remote Procedure Calls cannot fully answer to these requirements. The PS Data Subscription Mechanism addresses the above-mentioned problems: · it allows a client application in a Workstation to dynamically request accelerator data synchronised to a particular beam; · the client collects data related to the same beam from different front-ends The paper exposes the CERN PS specific requirements, and the solution proposed, based on functional data-groups and providing the additional functionality of monitoring process data (i.e., send on change).